I've had a squeak on the front of this engine for half a year, and it's recently gotten worse.  At first it only seemed to happen in cold or wet weather around idle RPMs, but now it's happening all the time.  I know it can be either the belt or the pulleys, and that there's ways to check for both.  I've already recently replaced the belt tensioner assembly and both idler pulleys.  Belt was replaced almost a year ago with an AC Delco belt. 

I tried cleaning the pulleys with brake cleaner and the belt with paper towels.  Scuffed the belt surface with a fine sandpaper, and put a fine crosshatch on the new idler pulleys.  No apparent change in the the noise after doing this.  Tried hitting each pulley in turn with WD-40 between startup tests, and it either stayed the same or got a little worse.  I don't know, maybe I should be using a thicker lubricant for bearing testing.  The squeak sounds closer to the right-hand side of the engine near the AC compressor.  I'd like to suspect the aftermarket belt, but the noise didn't change at all after cleaning and scuffing.

Really want to identify this squeak so I can fix it.  Anyone recognize it?  Any guesses or tests I can try?  Video:
 

 

Edited April 10, 20241 yr by dirty_mech

No noise in the morning until the engine warmed up, then the chirping began.  So I parked it and swapped out the new belt with the old once (since I like to keep the old one as a backup).  Noise instantly gone.  It was the belt, despite sounding so much like a bad pulley.

Searched and it appears Bando may be the OEM supplier.  Belt is also 1/3 the price of the AC Delco 6K864.  Will run the Bando for the summer and see if it develops any noise.  Perhaps I offroad it too much, and the dust messes with the belt, causing squeaking, and I'll have to replace it more frequently.

Changed the belt and the noise went away?

Maybe it's not the belt, but the tension that changed?

That squeak sounds like a bearing noise to me.